You know that water is a liquid, ice is a solid, and steam is a gas. But what exactly is a gas? The molecules in a solid are stable. They don’t move and they’re packed closely together. The molecules in a liquid are spaced farther apart. But the molecules in a gas are active. They move...

The inventor, Thomas Edison, loved learning and experimenting. His mother taught him at home and let him create a chemistry lab in the basement. As a young teenager, Edison got a job working on a train. He was kicked off the train after one of his science experiments set a train car on fire. The...